The present invention relates generally to the field of wireless radio transceivers, and more specifically, to the field of providing a multi-leveled power amplifier circuit for use in battery powered wireless radio transceivers. Such wireless radio transceivers are used in wireless telephone systems such as code division multiple access (CDMA), time division multiple access (TDMA), and advanced mobile phone services (AMPS) with the systems operating at multiple frequency ranges.
In battery powered radio transceivers, the maximum transmitted power is typically limited by the magnitude of the battery voltage. An additional concern with battery powered radio transceivers is the need to minimize battery energy drain, or the current drained from the battery, thereby maximizing battery life. Therefore, there is a trade-off between maximizing transmitted power to maximize usable range and minimizing battery energy drain to maximize battery life. This problem is compounded when the radio transceiver is used in an automotive application, where said radios are typically used in the outer fringes of the coverage area of base stations. Power amplifying circuitry has been proposed that uses a secondary battery, such as an automobile battery, to provide the energy source to increase the maximum transmitted power.
Previously proposed power amplifying circuits have typically dealt with radio transceivers operating in older AMPS systems, which operate in a single frequency range around 800 megahertz (MHz). However, with the newly adopted digital wireless cellular telephone standards TDMA and CDMA, cellular telephones are able to operate at multiple different frequency ranges, an example being the operation of CDMA systems at frequency ranges of 800 megahertz (MHz) or 1.9 Gigahertz (GHz). The resulting dual mode battery powered radio transceivers which support these standards must also operate at different frequency ranges, hence the power amplifying circuitry must also support multiple operating frequency ranges.
There is, therefore, a need in the industry for a system addressing these problems, as well as other related and unrelated problems.